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788 MEP141 – Effects of ColdZyme® mouth spray on upper respiratory tract infection (URTI) duration and viral load in endurance athletes


Background We have previously shown a reduction in URTI-symptom duration in endurance athletes in an open label trial with ColdZyme (Davison et al., 2020).

Objective To assess the efficacy of ColdZyme on URTI parameters, and respiratory pathogen detection/viral load, in a randomised placebo-controlled trial, under free-living conditions in athletes.

Design and Participants Fifty seven endurance athletes were randomised to placebo or ColdZyme and monitored for 3-months (between December 2022 – April 2023). Fifty two completed data collection, including daily Jackson common cold questionnaires, and collected throat swabs on days 1, 3, 5, and 7 of perceived URTI. Block randomisation was used to allow interim analysis after 1 winter season (allowing n = 24 to be unblinded to date).

Results At least one episode was recorded during the study in ~65% of participants. At least one respiratory pathogen was detected in 100% of cases (including several that would be excluded by traditional Jackson scoring criteria). The most common pathogens were Rhinovirus (detected in n = 19 cases) and H.Influenzae (detected in n = 14). Other pathogens were infrequently detected. For accurate comparisons of URTI incidence and duration we estimate a sample size 120–200 will be required, so we focus only on viral load for Rhinovirus here. Within the 24 unblinded datasets, 19 Rhinovirus-positive URTIs were recorded. Viral load peaked between days 1–5 (average at day 3), and was lower in the treatment vs placebo group (days 1–7 AUC relative quantification: placebo = 103 ×10–3-fold, ColdZyme = 20 ×10–3-fold, P = 0.038).

Conclusions These data suggest that ColdZyme may shorten the duration of a rhinovirus URTI via a reduction in viral load. Continuation of the study over subsequent winters is warranted to attain sufficient statistical power for comparison of URTI episode data and/or other pathogens using fully quantitative methods.

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